The present disclosure relates to electrode active materials used in lithium ion devices, such as rechargeable lithium ion batteries.
Lithium ion batteries, also known as Li-ion Batteries or LIB's are widely used in consumer electronics, for example in mobile telephones, tablets and laptops. LIB's are also used in other fields, such as military uses, electric vehicles and aerospace applications. During discharge of the battery, lithium ions (Li-ions) travel from a high-energy anode material through an electrolyte and a separator to a low-energy cathode material. During charging, energy is used to transfer the Li-ions back to the high-energy anode assembly. The charge and discharge processes in batteries are slow processes, and can degrade the chemical compounds inside the battery over time. Rapid charging causes accelerated degradation of the battery constituents, as well as a potential fire hazard due to a localized, over-potential build-up and increased heat generation—which can ignite the internal components, and lead to explosion.
Typical Li-ion battery anodes contain mostly graphite. Silicon or germanium, as anode-alloying components, generally exhibit higher lithium absorption capacities in comparison to anodes containing only graphite. Such silicon-containing or germanium-containing electrodes, however, usually exhibit poor life cycle and poor coulombic efficiency due to the mechanical expansion of silicon and germanium upon alloying with lithium, and upon lithium extraction from the alloy, which reduce the silicon alloy volume. Such mechanical instability results in the material breaking into fragments.